The coefficient of x⁷ in (1-2x+3x²-4x³+……..∞)^-4 is

The 3^rd term of ⁴ (3x-y³)is

5^th term of (2x²+3/x)⁵ is 10. Then x=

The coefficient of xⁿ in(1+x)²/(1-x)² is

The term independent of x in (x+1/x)⁶ is

The sum of the coefficients of even powers of x in the expansion of (1+x+x²)¹⁵ is